Wire electric discharge machining device and wire electric discharge machining method

Abstract

A wire electrical discharge machining device (100) comprises: a moving device (3); a control unit; a processing tank (6) that accommodates a workpiece (W) and stores a processing liquid (10); and a container (9) that is disposed above the workpiece (W), has a capacity with which it is possible to cover the workpiece (W), and is such that only a bottom surface facing the workpiece (W) opens. The container (9) can be changed to a first state in which a side surface (9c) contracts and in which an opening (9a) and an upper surface (9b) are positioned below the liquid surface (10a) of the processing liquid (10) in the processing tank (6), and a second state in which the side surface (9c) extends, the opening (9a) is positioned below the liquid surface (10a), and the upper surface (9b) is positioned above the liquid surface (10a). The container (9) being changed from the first state to the second state allows the the processing liquid (10) to be filled inside the container (9) until the container (9) is positioned above the liquid surface (10a). The workpiece (W) can enter the interior of the container (9) in the second state as the electric discharge machining progresses.

Description

Wire electric discharge machining apparatus and wire electric discharge machining method

[0001] The present disclosure relates to a wire electric discharge machining apparatus and a wire electric discharge machining method for electric discharge machining of a workpiece by generating an electric discharge between a wire electrode and the workpiece.

[0002] 2. Description of the Related Art Wire electric discharge machining apparatuses are known that apply a voltage between a wire electrode and a workpiece to generate an electric discharge, thereby melting the workpiece and machining the workpiece with an electric discharge.

[0003] As disclosed in Patent Document 1, a wire electric discharge machining apparatus typically includes a machining tank that stores an insulating machining fluid, and generates an electric discharge between a wire electrode and a workpiece in the machining fluid to machine the workpiece. The reason for performing electric discharge machining in this manner is to achieve benefits such as cooling the wire electrode and the workpiece, preventing fires, and removing machining waste generated by electric discharge machining. By machining the workpiece with electric discharge, a machining groove is formed in the workpiece.

[0004] Japanese Patent Application Laid-Open No. 2014-656

[0005] When a workpiece is machined by electrical discharge machining by moving the workpiece from below to above the wire electrode, the machining groove rises above the wire electrode as the electrical discharge machining progresses. As the electrical discharge machining progresses and the machining groove rises above the surface of the machining fluid, the surface tension of the machining fluid accumulated in the machining groove acts to narrow the machining groove. Therefore, if the workpiece is thin and lacks sufficient rigidity, the workpiece may deform, causing the machining groove to narrow. When the machining groove narrows, the flow of the machining fluid makes it difficult to remove machining debris from the groove, resulting in abnormal electrical discharges and wire electrode breakage, which can lead to reduced machining quality and reduced productivity.

[0006] One possible solution to this problem is to increase the depth of the machining tank to raise the level of the machining fluid so that the workpiece can be fully immersed in the machining fluid. However, when the workpiece is machined by moving it from below to above the wire electrode, the wire electrode is positioned in contact with the upper edge of the workpiece at the start of the machining, but is positioned at the lower edge of the workpiece at the end of the machining. Therefore, this method requires the depth of the machining tank to be at least twice the height of the workpiece, which results in an increase in the overall size of the wire-cut electrical discharge machining apparatus.

[0007] Another possible solution to the above problem is a method of electrical discharge machining by moving the workpiece from above to below relative to the wire electrode, as disclosed in Patent Document 1. This method is effective in solving the above problem because the machining groove formed in the workpiece by electrical discharge machining is gradually immersed in the machining fluid. However, this method has the risk of making the electrical discharge unstable because the machining fluid is vaporized by the heat of the electrical discharge and the bubbles generated by the vaporization of the machining fluid tend to accumulate in the machining groove where the electrical discharge phenomenon occurs.

[0008] The present disclosure has been made in consideration of the above, and aims to provide a wire electric discharge machining apparatus that can electric discharge machine a workpiece while the entire workpiece is immersed in machining fluid, while preventing the overall size of the wire electric discharge machining apparatus from increasing, even when the workpiece is electric discharge machined by moving it from below to above relative to a wire electrode.

[0009] To solve the above-mentioned problems and achieve the object, the present disclosure provides a wire electric discharge machining apparatus that generates an electric discharge between a wire electrode and a workpiece to machine the workpiece with an electric discharge, the wire electric discharge machining apparatus comprising: a moving device that moves the wire electrode and the workpiece relative to one another; and a control unit that controls the moving device. The wire electric discharge machining apparatus also comprises: a machining tank that accommodates the workpiece and stores a machining fluid; and a container that is positioned above the workpiece, has a capacity sufficient to cover the workpiece, and is open only on a bottom surface facing the workpiece. The container has an upper surface that is positioned above and spaced from the bottom opening, and side surfaces that extend from the upper surface to the opening and are formed to be expandable and contractible in the vertical direction. The container is changeable between a first state in which the side surfaces contract and the opening and the upper surface are positioned below the level of the machining fluid in the machining tank; and a second state in which the side surfaces expand and the opening is positioned below the level of the machining fluid in the machining tank and the upper surface is positioned above the level of the machining fluid in the machining tank. By changing the container from the first state to the second state, the inside of the container is filled with machining fluid up to a level above the machining fluid level in the machining tank. The workpiece can enter the inside of the container in the second state as the electric discharge machining progresses.

[0010] The wire electric discharge machining apparatus according to the present disclosure has the advantage that, even when the workpiece is electric discharge machined by moving it from below to above relative to the wire electrode, the wire electric discharge machining apparatus can be prevented from becoming too large overall, and the workpiece can be electric discharge machined while the entire workpiece is immersed in the machining fluid.

[0011] 5 is a cross-sectional view taken along line VI-VI of FIG. 5, showing the wire electrode and the workpiece during electrical discharge machining in the first embodiment, showing a state in which bubbles have formed inside the container; and FIG. 6 is a front view showing the container, wire electrode, and the workpiece during electrical discharge machining in the first embodiment, showing a state in which a side surface of the container has contracted. FIG. 1 is a front view showing the periphery of a container, a wire electrode, and a workpiece during electrical discharge machining in a modified example of the first embodiment, showing a state in which bubbles have been generated inside the container; FIG. 2 is a front view showing the periphery of a container, a wire electrode, and a workpiece after electrical discharge machining has been completed in a modified example of the first embodiment, showing a state in which a layer of gas has been generated inside the container; FIG. 3 is a front view showing the periphery of a container, a wire electrode, and a workpiece during electrical discharge machining by a wire electrical discharge machining apparatus according to a second embodiment, showing a state in which bubbles and a layer of gas have been generated inside the container;

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wire electric discharge machining apparatus and a wire electric discharge machining method according to embodiments will be described in detail below with reference to the accompanying drawings.

[0013] First Embodiment. FIG. 1 is a perspective view showing the main components of a wire electric discharge machining apparatus 100 according to a first embodiment. The wire electric discharge machining apparatus 100 generates an electric discharge between a wire electrode 2 and a workpiece W to machine the workpiece W. The wire electric discharge machining apparatus 100 cuts the workpiece W into a plurality of plate-shaped members. FIG. 1 shows the X-, Y-, and Z-axes of a three-axis Cartesian coordinate system. The X-axis direction corresponds to the traveling direction of the wire electrode 2 on the workpiece W, i.e., the traveling direction of the wire electrode 2 relative to the workpiece W placed in the wire electric discharge machining apparatus 100. An arrow 101 in FIG. 1 indicates the traveling direction of the wire electrode 2 on the workpiece W. The Y-axis direction corresponds to the direction in which the wire electrode 2 is arranged side by side on the workpiece W, i.e., the direction in which the wire electrode 2 is arranged side by side relative to the workpiece W placed in the wire electric discharge machining apparatus 100. The Z-axis direction corresponds to the height direction of the wire electric discharge machining apparatus 100. The height direction of the wire electric discharge machining apparatus 100 corresponds to the up-and-down direction.

[0014] The wire electric discharge machining apparatus 100 includes a plurality of guide rollers 1, a wire electrode 2, a moving device 3, a power supply 4, and a control unit 5. The wire electric discharge machining apparatus 100 also includes a machining tank 6, a machining fluid tank 7, a machining fluid nozzle 8, and a container 9. Examples of materials for the workpiece W include tungsten, molybdenum, silicon carbide, single crystal silicon, single crystal silicon carbide, gallium nitride, and polycrystalline silicon. Silicon carbide is also called silicon carbide.

[0015] The multiple guide rollers 1 serve to guide the travel of the wire electrode 2. Each guide roller 1 is cylindrical and extends in the Y-axis direction. The guide rollers 1 are rotated by a motor (not shown). In this embodiment, the number of guide rollers 1 is four, but a number other than four may be used. Hereinafter, when distinguishing between the four guide rollers 1, they will be referred to as guide rollers 1a, 1b, 1c, and 1d. Each of the guide rollers 1a, 1b, 1c, and 1d is arranged to be rotatable about the Y-axis. The rotation axes of the guide rollers 1a, 1b, 1c, and 1d are parallel to each other. Since the rotation axes of the guide rollers 1a, 1b, 1c, and 1d are parallel to each other, the wire electrode 2 can be traveled with high precision.

[0016] The guide rollers 1a, 1b, 1c, and 1d are arranged spaced apart from each other in the X-axis and Z-axis directions in a plane perpendicular to the rotation axes (in the XZ plane in FIG. 1 ). Specifically, the guide rollers 1a and 1b are arranged at the same height and spaced apart from each other in the X-axis direction. The guide rollers 1c and 1d are arranged at the same height and spaced apart from each other in the X-axis direction. The guide roller 1c is arranged below the guide roller 1b and spaced apart from it, and the guide roller 1d is arranged below the guide roller 1a and spaced apart from it. The rotation axes of the guide rollers 1a, 1b, 1c, and 1d are arranged at positions that coincide with the vertices of a rectangle. The guide rollers 1a and 1b are arranged above the machining tank 6 and spaced apart from it. The guide rollers 1c and 1d are arranged inside the machining tank 6. Part or all of the guide rollers 1c and 1d are immersed in the machining fluid 10 in the machining tank 6.

[0017] The wire electrode 2 serves to cut the workpiece W. One wire electrode 2 is unwound from a winding bobbin (not shown) and wound repeatedly around guide roller 1a, guide roller 1b, guide roller 1c, and guide roller 1d in this order. Specifically, the wire electrode 2 is wound multiple times at intervals around the outer circumferential surfaces of the guide rollers 1a, 1b, 1c, and 1d in a direction along the rotation axes of the guide rollers 1a, 1b, 1c, and 1d.

[0018] The wire electrode 2 has a plurality of cutting wire portions 2a that cut the workpiece W. The plurality of cutting wire portions 2a are arranged side by side at a distance from one another and face the workpiece W. The plurality of cutting wire portions 2a are portions of the wire electrode 2 that are stretched between the guide rollers 1c and 1d. The plurality of cutting wire portions 2a are arranged side by side at a distance from one another in a direction along the rotation axes of the guide rollers 1c and 1d. It is preferable that the plurality of cutting wire portions 2a be arranged parallel to one another. The wire electrode 2 travels in conjunction with the rotation of the guide rollers 1a, 1b, 1c, and 1d and is finally wound from the guide roller 1b onto a take-up bobbin (not shown).

[0019] The electron feeders 4 feed power to the wire electrode 2 to generate a discharge between the wire electrode 2 and the workpiece W. The electron feeders 4 are cylindrical and extend in the Y-axis direction. In this embodiment, there are two electron feeders 4, but this number may be changed as appropriate. Hereinafter, when the two electron feeders 4 need to be distinguished, they will be referred to as electron feeders 4a and 4b. Each of the electron feeders 4a and 4b is in contact with the wire electrode 2. Specifically, each of the electron feeders 4a and 4b is disposed below the corresponding cutting wire 2a and in contact with the corresponding cutting wire 2a. The electron feeders 4a and 4b are disposed spaced apart from each other in the X-axis direction, sandwiching the workpiece W therebetween.

[0020] One of the power supply terminals, 4a, is disposed in the X-axis direction between the guide roller 1c and a machining fluid nozzle 8a (described later). The other power supply terminal, 4b, is disposed in the X-axis direction between the guide roller 1d and a machining fluid nozzle 8b (described later). The wire electric discharge machining apparatus 100 is equipped with a machining power supply such as a power panel (not shown). Power supply terminals of the machining power supply are electrically connected to each of the power supply terminals 4a and 4b. A ground terminal of the machining power supply is electrically connected to the workpiece W. A voltage (voltage pulse) output from the machining power supply is applied between each cutting wire portion 2a of the wire electrode 2 and the workpiece W. This allows electric discharge to be generated between each cutting wire portion 2a and the workpiece W.

[0021] The moving device 3 serves to move the wire electrode 2 and the workpiece W relative to each other. Specifically, the moving device 3 changes the relative position of each cutting wire portion 2a and the processing stage 11 on which the workpiece W is placed. In this embodiment, the position of each cutting wire portion 2a in the Z-axis direction (vertical direction) is fixed, and the processing stage 11 and the workpiece W can be moved in the vertical direction by the moving device 3. The moving device 3 is disposed below the processing stage 11 and the workpiece W. The upper end of the moving device 3 is fixed to the processing stage 11. The workpiece W is fixed to the moving device 3 via the processing stage 11. Most of the moving device 3 is disposed at the bottom 6a of the processing tank 6. Part of the moving device 3 is disposed inside the processing tank 6.

[0022] The wire electric discharge machining device 100 performs electric discharge machining on the workpiece W by moving the machining stage 11, on which the workpiece W is placed, toward or away from the cutting wire portion 2a. Furthermore, by electric discharge machining of the workpiece W, a machining groove W1 (described below) is formed in the workpiece W along the cutting wire portion 2a. Finally, the workpiece W is cut into a plurality of plate-like members. The moving device 3 may be movable in the X-axis, Y-axis, and Z-axis directions.

[0023] The control unit 5 controls the moving device 3 and the machining power supply. The control unit 5 drives the moving device 3 to control the relative position of each cutting wire 2 a and the machining stage 11 on which the workpiece W is placed. The control unit 5 outputs a voltage application command to the machining power supply to control it so that an electric discharge occurs between each cutting wire 2 a and the workpiece W.

[0024] The machining tank 6 serves to accommodate the workpiece W and to store the machining fluid 10. The machining tank 6 is shaped like a box with an open top. The cutting wires 2a and the workpiece W, where discharge occurs, are immersed in the machining fluid 10 in the machining tank 6. The machining fluid 10 serves to cool the wire electrodes 2 and the workpiece W, prevent fires, and remove machining chips generated by electric discharge machining.

[0025] The machining fluid tank 7 is disposed outside the machining tank 6 and serves to temporarily store the machining fluid 10. The machining fluid tank 7 is shaped like a hollow box. When an operator is performing preparation work for the machining tank 6, such as setting the workpiece W inside the machining tank 6, the machining fluid 10 is temporarily stored inside the machining fluid tank 7. The machining fluid 10 is discharged from the machining tank 6 to the machining fluid tank 7 and supplied from the machining fluid tank 7 to the machining tank 6 by a water supply and drainage mechanism (not shown). The water supply and drainage mechanism includes a pump, piping, etc. The water supply and drainage mechanism manages the level 10a of the machining fluid 10 in the machining tank 6 to maintain an appropriate height. Specifically, when the level 10a of the machining fluid 10 in the machining tank 6 is higher than a predetermined reference height, the machining fluid 10 is discharged from the machining tank 6 to the machining fluid tank 7. On the other hand, when the liquid level 10 a of the machining fluid 10 in the machining tank 6 is lower than a preset reference height, the machining fluid 10 is supplied from the machining fluid tank 7 to the machining tank 6 .

[0026] The machining fluid nozzles 8 spray machining fluid 10 toward the gap between the wire electrode 2 and the workpiece W to remove machining debris generated by electrical discharge machining. Two machining fluid nozzles 8 are disposed on either side of the workpiece W in the X-axis direction. In this embodiment, two machining fluid nozzles 8 are provided, but this number may be changed as appropriate. Hereinafter, when distinguishing between the two machining fluid nozzles 8, they will be referred to as machining fluid nozzles 8a and 8b. Each of the machining fluid nozzles 8a and 8b is disposed above and spaced apart from the corresponding cutting wire 2a. One of the machining fluid nozzles, 8a, is disposed between the workpiece W and the power supply 4a in the X-axis direction. The other machining fluid nozzle, 8b, is disposed between the workpiece W and the power supply 4b in the X-axis direction. The machining fluid nozzles 8 are supplied with machining fluid from the machining fluid tank 7 through a machining fluid supply pipe (not shown).

[0027] FIG. 2 is a front view showing a procedure for filling the interior of the container 9 with machining fluid 10 in the first embodiment, illustrating a state in which the side surface 9c of the container 9 is contracted. FIG. 3 is a front view showing a procedure for filling the interior of the container 9 with machining fluid 10 in the first embodiment, illustrating a state in which the side surface 9c of the container 9 is expanded. As shown in FIGS. 2 and 3 , the container 9 is disposed above the workpiece W and has a capacity sufficient to cover the workpiece W. The container 9 is disposed near the liquid surface 10a of the machining fluid 10 in the machining tank 6. Only the bottom surface of the container 9 facing the workpiece W is open. The bottom surface of the container 9 has an opening 9a penetrating the bottom surface in the vertical direction. That is, the surfaces and sides of the container 9 other than the bottom surface are sealed.

[0028] The container 9 has a top surface 9b positioned above and spaced from the opening 9a on the bottom surface, and a side surface 9c extending from the top surface 9b to the opening 9a and formed to be expandable and contractable in the vertical direction. The container 9 is fixed to surrounding components with the opening 9a positioned below the liquid level 10a of the machining fluid 10 in the machining tank 6. In this embodiment, the container 9 is fixed to the top surfaces of the machining fluid nozzles 8a and 8b, but may also be fixed to other components. The side surface 9c is formed in a bellows shape that is expandable and contractable in the vertical direction. The side surface 9c is a cylindrical surface extending downward from the periphery of the top surface 9b. A linear actuator 12 is connected to the top surface 9b. By moving the top surface 9b in the vertical direction using the linear actuator 12, the side surface 9c can be expanded and contracted in the vertical direction, thereby changing the capacity of the container 9.

[0029] Specifically, the container 9 can be changed between a first state in which the side surface 9c contracts and the opening 9a and the top surface 9b are located below the liquid level 10a of the machining fluid 10 in the machining tank 6, as shown in Fig. 2, and a second state in which the side surface 9c expands and the opening 9a is located below the liquid level 10a of the machining fluid 10 in the machining tank 6 and the top surface 9b is located above the liquid level 10a of the machining fluid 10 in the machining tank 6, as shown in Fig. 3. By changing the container 9 from the first state to the second state, the machining fluid 10 is filled inside the container 9 until it is located above the liquid level 10a of the machining fluid 10 in the machining tank 6. That is, by expanding the side surface 9c until the top surface 9b of the container 9 is located above the liquid level 10a of the machining fluid 10 in the machining tank 6, the liquid level 10b of the machining fluid 10 in the container 9 is located above the liquid level 10a of the machining fluid 10 in the machining tank 6. As the electric discharge machining progresses, the workpiece W can enter the interior of the container 9 in the second state.

[0030] When the workpiece W is a semiconductor wafer material, the workpiece W is often pre-formed into a cylindrical shape so that the plate-like member (semiconductor wafer) cut from the workpiece W will be a thin circular plate. A certain voltage is applied to the interelectrode gap between each cutting wire 2a and the workpiece W. When the interelectrode distance reaches a certain range, an electric discharge occurs between the electrodes, causing the cutting wire 2a to heat up and melt the workpiece W. As a result, multiple plate-like members are cut from the workpiece W at once. During cutting, machining fluid 10 is supplied to the gaps between each cutting wire 2a and the workpiece W to remove machining debris generated between the cutting wire 2a and the workpiece W. Because machining debris can cause short circuits between the cutting wire 2a and the workpiece W, supplying machining fluid 10 to the gaps between each cutting wire 2a and the workpiece W reduces the frequency of short circuits.

[0031] Next, with reference to FIGS. 1 to 8 , a wire electrical discharge machining method for electrical discharge machining of a workpiece W using the wire electrical discharge machining apparatus 100 according to the present embodiment will be described. FIG. 4 is a flowchart showing the steps of the wire electrical discharge machining method using the wire electrical discharge machining apparatus 100 according to the first embodiment. FIG. 5 is a front view showing the periphery of the container 9, the wire electrode 2, and the workpiece W during electrical discharge machining in the first embodiment. FIG. 6 is a cross-sectional view taken along line VI-VI shown in FIG. 5 , showing the periphery of the wire electrode 2 and the workpiece W during electrical discharge machining in the first embodiment. FIG. 7 is a front view showing the periphery of the container 9, the wire electrode 2, and the workpiece W during electrical discharge machining in the first embodiment, showing a state in which bubbles 14 have been generated inside the container 9. FIG. 8 is a front view showing the periphery of the container 9, the wire electrode 2, and the workpiece W after electrical discharge machining in the first embodiment has been completed, showing a state in which a layer of gas 15 has been generated inside the container 9.

[0032] The wire electric discharge machining method includes a storing step, a filling step, and a machining step.

[0033] The storage step is a step of storing machining fluid 10 inside machining tank 6 shown in FIG. 1 . In the storage step, steps S1 and S2 shown in FIG. 4 are performed. In the storage step, machining fluid 10 is supplied from machining fluid tank 7 into machining tank 6 (step S1). This causes the liquid level 10a of machining fluid 10 in machining tank 6 to rise. Next, in the storage step, it is confirmed whether the liquid level 10a of machining fluid 10 in machining tank 6 has reached a preset height (step S2). If the liquid level 10a of machining fluid 10 in machining tank 6 has not reached the preset height (No in step S2), the system waits while continuing to supply machining fluid 10 into machining tank 6. Whether the liquid level 10a of machining fluid 10 in machining tank 6 has reached the preset height is determined by a liquid level sensor (not shown). The preset height must be above the opening 9a of container 9. When the liquid level 10a of the machining fluid 10 in the machining tank 6 reaches a preset height (Yes in step S2), the supply of the machining fluid 10 into the machining tank 6 is stopped, and the process proceeds to the next filling step. Note that the container 9 may be placed inside the machining tank 6 after the machining fluid 10 is supplied into the machining tank 6 to raise the liquid level 10a of the machining fluid 10 in the machining tank 6, or the container 9 may be placed inside the machining tank 6 after the machining fluid 10 is supplied into the machining tank 6 to raise the liquid level 10a of the machining fluid 10 in the machining tank 6.

[0034] As shown in FIGS. 2 and 3 , the filling step is a step in which, before the start of electric discharge machining, the upper surface 9 b of the container 9 is raised, the interior of the container 9 is filled with machining fluid 10, and a space 13 is created inside the container 9 where machining fluid 10 is filled to a position higher than the liquid level 10 a of the machining fluid 10 in the machining tank 6. In the filling step, the processing of step S3 shown in FIG. 4 is performed. As shown in FIG. 3 , in the filling step, the upper surface 9 b of the container 9 is raised by the linear actuator 12. Before the filling step, the container 9 is in the first state shown in FIG. 2 . That is, the side surface 9 c of the container 9 contracts vertically, and the entire container 9 is located below the liquid level 10 a of the machining fluid 10 in the machining tank 6. When the upper surface 9 b of the container 9 is raised by the linear actuator 12 from the first state, the container 9 enters the second state shown in FIG. 3 . In other words, the side surface 9c of the container 9 extends in the vertical direction, so that the opening 9a and part of the side surface 9c are positioned below the liquid level 10a of the machining fluid 10 in the machining tank 6, and the top surface 9b and the remaining part of the side surface 9c are positioned above the liquid level 10a of the machining fluid 10 in the machining tank 6.

[0035] When the container 9 enters the second state, the pressure inside the container 9 decreases, and the pressure inside the container 9 is balanced with the atmospheric pressure acting on the liquid level 10a of the machining fluid 10 in the machining tank 6. As a result, the machining fluid 10 in the machining tank 6 flows into the inside of the container 9, creating a space 13 inside the container 9 filled with the machining fluid 10 to a position higher than the liquid level 10a of the machining fluid 10 in the machining tank 6. That is, the liquid level 10b of the machining fluid 10 in the container 9 is positioned higher than the liquid level 10a of the machining fluid 10 in the machining tank 6. In the filling step, the upper surface 9b of the container 9 is simply raised to a position where the container 9 and the workpiece W do not come into contact with each other when performing the machining step described below. In addition, in the filling step, the amount by which the upper surface 9b of the container 9 is raised (the amount of movement of the linear actuator 12) can be appropriately adjusted depending on the size of the workpiece W.

[0036] As shown in FIG. 5 , the machining step involves performing electrical discharge machining while moving the workpiece W, and moving the workpiece W into the container 9 as the electrical discharge machining progresses. In the machining step, steps S4 to S6 shown in FIG. 4 are performed. In the machining step, electrical discharge machining is started (step S4). Specifically, a voltage output from the machining power supply is applied between each cutting wire 2 a and the workpiece W, thereby generating an electrical discharge between each cutting wire 2 a and the workpiece W. Also, in the machining step, the moving device 3 starts moving upward toward a preset electrical discharge machining completion position, and starts moving the workpiece W upward at an appropriate speed. As the workpiece W is moved upward relative to the wire electrode 2, electrical discharges generated between each cutting wire 2 a and the workpiece W melt the workpiece W.

[0037] As shown in Fig. 6 , when the moving device 3 is further moved upward to move the workpiece W further upward relative to the wire electrode 2, electrical discharge machining of the workpiece W progresses, and multiple machining grooves W1 are formed in the workpiece W. As shown in Figs. 7 and 8 , the workpiece W moves upward as electrical discharge machining progresses and enters the interior of the container 9 in the second state. Next, in the machining step, it is confirmed whether the moving device 3 has moved to the position where electrical discharge machining is completed (step S5). If the moving device 3 has not moved to the position where electrical discharge machining is completed (No in step S5), the moving device 3 continues to move upward and waits. If the moving device 3 has moved to the position where electrical discharge machining is completed (Yes in step S5), the moving device 3 is stopped, and electrical discharge machining is completed (step S6).

[0038] As shown in Fig. 7, during electrical discharge machining, the machining fluid 10 evaporates due to the heat of electrical discharge machining, generating bubbles 14, or the bubbles 14 become mixed into the machining fluid 10 sprayed from the machining fluid nozzle 8. These bubbles 14 cause gas 15, such as air or gas, to accumulate inside the container 9, creating a layer of gas 15, as shown in Fig. 8. Therefore, the liquid level 10c of the machining fluid 10 in the container 9 after the completion of electrical discharge machining, as shown in Fig. 8, is located lower than the liquid level 10b of the machining fluid 10 in the container 9 at the start of electrical discharge machining, as shown in Fig. 3. Therefore, assuming that gas 15 will accumulate inside the container 9, the volume of the container 9 should be designed to be sufficiently large so that the workpiece W will not be exposed to the layer of gas 15 during electrical discharge machining.

[0039] Next, the effects of the wire electric discharge machining apparatus 100 according to this embodiment will be described.

[0040] 2 and 3 , the wire electric discharge machining apparatus 100 includes a container 9 disposed above a workpiece W, having a capacity large enough to cover the workpiece W, and having only a bottom surface open facing the workpiece W. In this embodiment, the container 9 has a top surface 9b disposed above and spaced from the bottom opening 9a, and a side surface 9c extending from the top surface 9b to the opening 9a and formed to be expandable and contractible in the vertical direction. In this embodiment, the container 9 can be changed between a first state in which the side surface 9c contracts and the opening 9a and the top surface 9b are positioned below the level 10a of the machining fluid 10 in the machining tank 6, and a second state in which the side surface 9c expands and the opening 9a is positioned below the level 10a of the machining fluid 10 in the machining tank 6 and the top surface 9b is positioned above the level 10a of the machining fluid 10 in the machining tank 6. Furthermore, in this embodiment, by changing the container 9 from the first state to the second state, the inside of the container 9 is filled with machining fluid 10 until it is positioned above the liquid level 10a of the machining fluid 10 in the machining tank 6. Furthermore, in this embodiment, the workpiece W can enter the inside of the container 9 in the second state as the electric discharge machining progresses. In short, in this embodiment, by filling the inside of the container 9 with machining fluid 10, a space 13 is locally created in which the liquid level 10b of the machining fluid 10 in the container 9 is higher than the liquid level 10a of the machining fluid 10 in the machining tank 6, and the workpiece W is electric discharge machined with the entire workpiece W immersed in the machining fluid 10 in this space 13. With this configuration, even when the workpiece W is electric discharge machined by moving the workpiece W from below to above the wire electrode 2, the machined groove W1 shown in Fig. 6 is prevented from being positioned above the liquid surface 10b of the machining fluid 10 in the container 9 shown in Fig. 5 (the machined groove W1 is exposed to the air), and the machined groove W1 is prevented from narrowing due to the surface tension of the machining fluid 10 accumulated in the machined groove W1. This makes it easy to discharge machining chips generated by electric discharge machining out of the machined groove W1 by the flow of the machining fluid 10, suppressing the occurrence of abnormal discharge and breakage of the wire electrode 2, thereby improving the machining quality of the workpiece W and improving the productivity of the workpiece W.

[0041] As shown in Figure 6, when multiple cutting wires 2a are arranged in parallel to cut multiple plate-shaped members from a workpiece W, some of the grooves W1 narrow due to the surface tension of the machining fluid 10 accumulated in the grooves W1, while others widen. This causes differences in the discharge of chips from each groove W1, resulting in variations in the machining quality of each plate-shaped member. In this regard, in this embodiment, the grooves W1 are prevented from being positioned above the liquid surface 10b of the machining fluid 10 in the container 9, thereby preventing the grooves W1 from narrowing or widening due to the surface tension of the machining fluid 10 accumulated in the grooves W1. This reduces the differences in the discharge of chips from each groove W1, thereby reducing variations in the machining quality of each plate-shaped member.

[0042] Furthermore, in the final stage of electrical discharge machining, the cross-sectional area of ​​the connection portion of the workpiece W, i.e., the uncut portion of the workpiece W, becomes very small compared to the area of ​​the machined groove W1, which causes a problem that the workpiece W may break due to the surface tension of the machining fluid 10 accumulated in the machined groove W1. In this regard, in this embodiment, the machined groove W1 is prevented from being positioned above the liquid surface 10b of the machining fluid 10 in the container 9, thereby preventing the workpiece W from breaking due to the surface tension of the machining fluid 10 accumulated in the machined groove W1.

[0043] In this embodiment, by adopting the configuration described in paragraph 0040, electric discharge machining is performed with the entire workpiece W immersed in the machining fluid 10, so the machining tank 6 can be made lighter and smaller than when the depth of the machining tank 6 is made at least twice the height of the workpiece W. This prevents the wire electric discharge machining apparatus 100 from becoming larger overall. It also reduces the amount of machining fluid 10 used.

[0044] In this embodiment, as shown in Figures 6 to 8, the workpiece W is moved from below to above relative to the wire electrode 2 to perform electrical discharge machining on the workpiece W. This makes it difficult for bubbles 14 generated by the evaporation of the machining fluid 10 to accumulate in the machining groove W1 where the electrical discharge phenomenon is occurring, thereby stabilizing the electrical discharge machining.

[0045] As described above, in this embodiment, even when the workpiece W is moved from below to above relative to the wire electrode 2 to perform electrical discharge machining on the workpiece W, the workpiece W can be electrical discharge machined while the entire workpiece W is immersed in the machining fluid 10, while preventing the overall size of the wire electrical discharge machining device 100 from increasing.

[0046] Next, a modification of the first embodiment will be described.

[0047] In this embodiment, as shown in Figures 7 and 8, the shape of the side surface 9c is illustrated as being generally parallel in the vertical direction from the opening 9a to the top surface 9b, with protrusions protruding into the container 9 and protrusions protruding out of the container 9 alternately and continuously formed. However, this is not limited to this. For example, as shown in Figures 9 and 10, the shape of the side surface 9c may be flared from the opening 9a to the top surface 9b. Figure 9 is a front view showing the vicinity of the container 9, the wire electrode 2, and the workpiece W during electric discharge machining in a modification of the first embodiment, illustrating the state in which bubbles 14 have been generated inside the container 9. Figure 10 is a front view showing the vicinity of the container 9, the wire electrode 2, and the workpiece W after electric discharge machining has been completed in a modification of the first embodiment, illustrating the state in which a layer of gas 15 has been generated inside the container 9.

[0048] The shape of the side surface 9c is such that the cross-sectional area of ​​the container 9 expands from bottom to top. This modification allows for an increased volume of the container 9. Therefore, even if a layer of gas 15 is created inside the container 9 due to bubbles 14 generated during electrical discharge machining, the workpiece W is not exposed to the layer of gas 15 during electrical discharge machining. The workpiece W can be electrical discharge machined while the entire workpiece W is immersed in the machining fluid 10. This prevents the machining groove W1 from narrowing due to the surface tension of the machining fluid 10 accumulated in the machining groove W1. This facilitates the discharge of machining chips generated during electrical discharge machining out of the machining groove W1 by the flow of the machining fluid 10. This prevents abnormal discharges and breakage of the wire electrode 2, thereby improving the machining quality of the workpiece W and improving the productivity of the workpiece W.

[0049] In this embodiment, the filling step and the machining step are performed at different times (the filling step is performed before the start of electrical discharge machining), but they may also be performed simultaneously. That is, the wire electrical discharge machining method may include a machining step that combines the above-described filling step and machining step. This machining step involves lifting the upper surface 9b of the container 9 shown in FIG. 5, filling the container 9 with machining fluid 10, creating a space 13 filled with machining fluid 10 within the container 9 until it is positioned above the liquid level 10a of the machining fluid 10 in the machining tank 6, and moving the workpiece W to perform electrical discharge machining. As the electrical discharge machining progresses, the workpiece W may be advanced into the container 9 while gradually lifting the upper surface 9b of the container 9 as the electrical discharge machining progresses.

[0050] Second Embodiment Next, a wire electric discharge machining apparatus 100A according to a second embodiment will be described with reference to FIGS. 11 and 12 . FIG. 11 is a front view showing the vicinity of the container 9, the wire electrode 2, and the workpiece W during electric discharge machining by the wire electric discharge machining apparatus 100A according to the second embodiment, illustrating a state in which a layer of bubbles 14 and gas 15 is generated inside the container 9. FIG. 12 is a front view showing the vicinity of the container 9, the wire electrode 2, and the workpiece W of the wire electric discharge machining apparatus 100A according to the second embodiment, illustrating a state in which the gas 15 accumulated inside the container 9 is being discharged. This embodiment differs from the first embodiment described above in that the gas 15 accumulated inside the container 9 during electric discharge machining is discharged to the outside of the container 9. In the second embodiment, parts that overlap with those in the first embodiment are designated by the same reference numerals, and descriptions thereof will be omitted.

[0051] The position of the workpiece W can be changed between a processing position where it enters the container 9 in the second state shown in Fig. 11 and a retracted position where it retracts to the outside of the container 9 in the first state shown in Fig. 12. When the container 9 is changed from the second state to the first state, the gas 15 accumulated inside the container 9 is discharged to the outside of the container 9.

[0052] Next, a wire electric discharge machining method for electric discharge machining a workpiece W using the wire electric discharge machining apparatus 100A according to the second embodiment will be described with reference to Figures 11 to 13. Figure 13 is a flowchart showing the steps of the wire electric discharge machining method using the wire electric discharge machining apparatus 100A according to the second embodiment.

[0053] The wire electric discharge machining method includes a storing step, a filling step, a machining step, an adjusting step, a retracting step, a discharging step, and a restarting step. The storing step (steps S11 and S12) and the filling step (step S13) are the same as the storing step (steps S1 and S2) and the filling step (step S3) of the wire electric discharge machining method according to the first embodiment described above, and therefore a description thereof will be omitted here.

[0054] The machining steps (steps S14, S16, and S17) of this embodiment are the same as the machining steps (steps S4, S5, and S6) of the wire electric discharge machining method according to the first embodiment described above. However, the machining steps of this embodiment differ from the machining steps of the wire electric discharge machining method according to the first embodiment in that it is determined (step S15) whether a certain amount of gas 15 or more has accumulated inside the container 9 during electric discharge machining. In the machining steps of this embodiment, if the certain amount of gas 15 or more has not accumulated inside the container 9 (No in step S15), it is confirmed (step S16) whether the moving device 3 has moved to the position where electric discharge machining is completed. Subsequently, in the machining steps, if the moving device 3 has not moved to the position where electric discharge machining is completed (No in step S16), the processing of step S15 is repeated. In the machining steps, if the moving device 3 has moved to the position where electric discharge machining is completed (Yes in step S16), the moving device 3 is stopped, and electric discharge machining is completed (step S17). On the other hand, in the processing step, if a certain amount or more of gas 15 accumulates inside the container 9 (Yes in step S15), the process proceeds to the adjustment step (step S18).

[0055] The adjustment step is a step for adjusting the voltage applied between the wire electrode 2 and the workpiece W when a certain amount of gas 15 accumulates inside the container 9 during electric discharge machining. In the adjustment step, the process of step S18 shown in FIG. 13 is performed. In the adjustment step, the voltage applied between each cutting wire 2a and the workpiece W is adjusted so that the electric discharge-machined portion of the workpiece W (machined groove W1) is not damaged by unexpected electric discharge. In the adjustment step, the voltage is reduced or the application of voltage is stopped. However, depending on the diameter of the wire electrode 2, the width of the machined groove W1, etc., the adjustment step may not be necessary. In such cases, the adjustment step may be omitted.

[0056] As shown in Fig. 12, the retraction step is a step in which the workpiece W is retracted to the outside of the container 9. In the retraction step, the processing of step S19 shown in Fig. 13 is performed. In the retraction step, the workpiece W is retracted to the outside of the container 9 so that the workpiece W and the container 9 do not come into contact with each other. In the retraction step, the movement of the moving device 3 starts downward, and the workpiece W starts to move downward at an appropriate speed. When the workpiece W is moved downward relative to the container 9, the position of the workpiece W is changed to the retracted position where it is retracted to the outside of the container 9 in the first state.

[0057] As shown in Fig. 12 , the discharge step is a step in which the upper surface 9b of the container 9 is pushed down toward the opening 9a to contract the side surface 9c, thereby discharging the gas 15 accumulated inside the container 9 to the outside of the container 9. In the discharge step, the processing of step S20 shown in Fig. 13 is performed. In the discharge step, the upper surface 9b of the container 9 is pushed down by the linear actuator 12. As a result, the side surface 9c of the container 9 contracts in the vertical direction, and the entire container 9 is positioned below the liquid level 10a of the machining fluid 10 in the machining tank 6, and the gas 15 accumulated inside the container 9 is discharged to the outside of the container 9. In other words, the container 9 is changed from the second state to the first state, so that the gas 15 accumulated inside the container 9 is discharged to the outside of the container 9.

[0058] As shown in FIG. 11 , the restart step involves lifting the top surface 9b of the container 9 away from the opening 9a to extend the side surface 9c, and then inserting the workpiece W into the container 9 to resume electrical discharge machining. In the restart step, steps S21 to S23 shown in FIG. 13 are performed. First, in the restart step, the linear actuator 12 lifts the top surface 9b of the container 9 (step S21). As a result, the side surface 9c of the container 9 extends in the vertical direction, so that the opening 9a and a portion of the side surface 9c are positioned below the liquid level 10a of the machining fluid 10 in the machining tank 6, and the remaining portions of the top surface 9b and the side surface 9c are positioned above the liquid level 10a of the machining fluid 10 in the machining tank 6. Next, in the restart step, the moving device 3 starts moving upward, moving the workpiece W upward at an appropriate speed, and returning the moving device 3 and the workpiece W to their pre-retracted positions (step S22). As a result, the position of the workpiece W is changed to the machining position where it enters the inside of the container 9 in the second state. Subsequently, in the restart step, a voltage output from the machining power supply is applied between each cutting wire portion 2 a and the workpiece W, thereby generating an electric discharge between each cutting wire portion 2 a and the workpiece W, and electric discharge machining is restarted (step S23).

[0059] In the wire electric discharge machining method according to this embodiment, electric discharge machining is performed by repeating the machining step, adjustment step, retraction step, discharge step, and restart step. The timing of the discharge step (the timing at which the gas 15 accumulated inside the container 9 is discharged to the outside of the container 9) can be set arbitrarily. For example, the relationship between the electric discharge machining time and the volume of the gas 15 accumulated inside the container 9 may be determined in advance by testing, and the discharge step may be performed when an arbitrarily set electric discharge machining time is reached. Furthermore, for example, a liquid level sensor 16 may be attached to the upper surface 9b of the container 9 shown in FIG. 11, and the discharge step may be performed when the liquid level 10c of the machining liquid 10 drops to an arbitrarily set position.

[0060] Next, the effects of the wire electric discharge machining apparatus 100A according to this embodiment will be described.

[0061] 11 and 12 , the position of the workpiece W can be changed between a machining position where the workpiece W enters the container 9 in the second state and a retracted position where the workpiece W retracts to the outside of the container 9 in the first state. Furthermore, in this embodiment, gas 15 accumulated inside the container 9 is discharged to the outside of the container 9 by changing the container 9 from the second state to the first state. With these configurations, even if the container 9 cannot be designed to be sufficiently large due to dimensional constraints of the wire electric discharge machining apparatus 100A, the workpiece W is not exposed to a layer of gas 15 during electric discharge machining, and the workpiece W can be machined while the entire workpiece W is immersed in the machining fluid 10. This prevents the machining groove W1 from narrowing due to the surface tension of the machining fluid 10 accumulated in the machining groove W1. This makes it easier to discharge the machining chips generated by the electric discharge machining outside the machining groove W1 by the flow of the machining fluid 10, thereby suppressing the occurrence of abnormal discharges and breakage of the wire electrode 2, thereby improving the machining quality of the workpiece W and improving the productivity of the workpiece W.

[0062] Third Embodiment Next, a wire electric discharge machining apparatus 100B according to a third embodiment will be described with reference to Figures 14 and 15. Figure 14 is a front view of the wire electric discharge machining apparatus 100B according to the third embodiment. Figure 15 is a front view of the wire electric discharge machining apparatus 100B according to the third embodiment, showing a state in which bubbles 14 generated inside the container 9 are being discharged. This embodiment differs from the first and second embodiments in that the container 9 is not extendable and that the wire electric discharge machining apparatus 100B includes a suction device 17. In the third embodiment, parts that overlap with those in the first and second embodiments are designated by the same reference numerals, and description thereof will be omitted.

[0063] The side surface 9c of the container 9 is not formed to be expandable and contractible in the vertical direction. The container 9 can be changed between a first state in which the entire container 9 is placed in the machining fluid 10 in the machining tank 6, as shown in Fig. 14, and a second state in which the opening 9a is located below the liquid level 10a of the machining fluid 10 in the machining tank 6 and the upper surface 9b is located above the liquid level 10a of the machining fluid 10 in the machining tank 6, as shown in Fig. 15. By changing the container 9 from the first state to the second state, the interior of the container 9 is filled with machining fluid 10 until it is located above the liquid level 10a of the machining fluid 10 in the machining tank 6. The workpiece W can enter the interior of the container 9 in the second state as the electric discharge machining progresses.

[0064] The suction device 17 is connected to the upper surface 9b of the container 9 and is a mechanism for sucking in bubbles 14 and gas 15 generated inside the container 9. The suction device 17 has a suction hose 17a and an aspirator 17b. One end of the suction hose 17a is connected to the upper surface 9b of the container 9 and communicates with the interior of the container 9. The other end of the suction hose 17a is disposed in the machining fluid 10 stored inside the machining fluid tank 7. The machining fluid tank 7 is located below the machining tank 6 and the container 9. The aspirator 17b is provided midway along the suction hose 17a.

[0065] Next, a wire electric discharge machining method for electric discharge machining a workpiece W using the wire electric discharge machining apparatus 100B according to this embodiment will be described with reference to FIGS.

[0066] The wire electric discharge machining method includes a storing step, a filling step, and a machining step. The filling step is the same as the filling step in the wire electric discharge machining method according to the first embodiment described above, and therefore a description thereof will be omitted here.

[0067] The storing step and machining step of this embodiment are generally the same as those of the wire electric discharge machining method according to the first embodiment described above, but differ from those of the wire electric discharge machining method according to the first embodiment in that bubbles 14 and gas 15 generated inside container 9 are sucked in by suction device 17. That is, as shown in Fig. 14, in the storing step of this embodiment, if gas 15 is generated inside container 9 during the process of placing container 9 in machining fluid 10 in machining tank 6, or during the process of placing container 9 inside machining tank 6 and then supplying machining fluid 10 into machining tank 6 to raise the liquid level 10a of machining fluid 10, gas 15 is sucked in by suction device 17. This allows gas 15 to be discharged to the outside of container 9, and allows the interior of container 9, suction hose 17a, and suction device 17b to be filled with machining fluid 10. 15 , when the upper surface 9b of the container 9 is raised by the linear actuator 12, the inside of the container 9 is filled with the machining fluid 10 until it is positioned above the liquid level 10a of the machining fluid 10 in the machining tank 6. In other words, the liquid level 10b of the machining fluid 10 in the container 9 is positioned above the liquid level 10a of the machining fluid 10 in the machining tank 6.

[0068] When performing the machining step, i.e., during electrical discharge machining, bubbles 14 may be generated as machining fluid 10 evaporates, or bubbles 14 may become mixed into machining fluid 10 sprayed from machining fluid nozzle 8. In this regard, as in the present embodiment, if the interior of container 9, the interior of suction hose 17a, and the interior of aspirator 17b are filled with machining fluid 10, bubbles 14 will continue to be discharged from the upper surface 9b of container 9 through suction hose 17a into the interior of machining fluid tank 7 due to the siphon principle, even if aspirator 17b is not operated. Therefore, in this embodiment, even if bubbles 14 are generated inside container 9 during electrical discharge machining, bubbles 14 can be quickly discharged to the outside of container 9.

[0069] Next, the effects of the wire electric discharge machining apparatus 100B according to this embodiment will be described.

[0070] 14 and 15 , wire electric discharge machining apparatus 100B is provided with suction device 17 connected to upper surface 9b of container 9 for sucking bubbles 14 and gas 15 generated inside container 9. With this configuration, bubbles 14 and gas 15 generated inside container 9 can be discharged to the outside of container 9.

[0071] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0072] 1, 1a, 1b, 1c, 1d guide roller, 2 wire electrode, 2a cutting wire portion, 3 moving device, 4, 4a, 4b power supply, 5 control portion, 6 machining tank, 6a bottom portion, 7 machining fluid tank, 8, 8a, 8b machining fluid nozzle, 9 container, 9a opening, 9b top surface, 9c side surface, 10 machining fluid, 10a, 10b, 10c fluid level, 11 machining stage, 12 linear motion actuator, 13 space, 14 air bubble, 15 gas, 16 fluid level sensor, 17 suction device, 17a suction hose, 17b suction device, 100, 100A, 100B wire electric discharge machining device, 101 arrow, W workpiece, W1 machining groove.

Claims

1. A wire electric discharge machining apparatus for electric discharge machining of a workpiece by generating an electric discharge between the wire electrode and the workpiece, comprising: a moving device for moving the wire electrode and the workpiece relatively; a control unit for controlling the moving device; a machining tank for accommodating the workpiece and storing machining fluid; and a container disposed above the workpiece and having a capacity sufficient to cover the workpiece, with only the bottom surface facing the workpiece being open, the container having an upper surface disposed above and spaced from the opening in the bottom surface, and side surfaces extending from the upper surface to the opening and formed to be expandable and contractible in the vertical direction, the container being changeable between a first state in which the side surfaces contract and the opening and the upper surface are positioned below the level of the machining fluid in the machining tank, and a second state in which the side surfaces expand and the opening is positioned below the level of the machining fluid in the machining tank and the upper surface is positioned above the level of the machining fluid in the machining tank, A wire electric discharge machining apparatus characterized in that, by changing the container from the first state to the second state, the inside of the container is filled with the machining fluid up to a position above the liquid level of the machining fluid in the machining tank, and the workpiece can enter the inside of the container in the second state as the electric discharge machining progresses.

2. A wire electric discharge machining apparatus for generating an electric discharge between a wire electrode and a workpiece to perform electric discharge machining on the workpiece, comprising: a moving device for moving the wire electrode and the workpiece relatively; a control unit for controlling the moving device; a machining tank for accommodating the workpiece and storing machining fluid; and a container disposed above the workpiece and having a capacity capable of covering the workpiece, with only the bottom surface facing the workpiece being open, the container having an upper surface disposed above and spaced from the opening in the bottom surface, and a side surface extending from the upper surface to the opening, the container being changeable between a first state in which the entire container is disposed in the machining fluid in the machining tank and a second state in which the opening is located below the level of the machining fluid in the machining tank and the upper surface is located above the level of the machining fluid in the machining tank, and by changing the container from the first state to the second state, the machining fluid fills the interior of the container until it is located above the level of the machining fluid in the machining tank, The wire electric discharge machining apparatus is characterized in that the workpiece can enter the interior of the container in the second state as electric discharge machining progresses.

3. A wire electric discharge machining device according to claim 1 or 2, wherein the shape of the side surface is a shape that widens from the opening toward the upper surface.

4. A wire electric discharge machining apparatus according to claim 1 or 2, further comprising a suction device connected to the top surface of the container for sucking out bubbles and gas generated inside the container.

5. The wire electric discharge machining device described in claim 1, characterized in that the position of the workpiece can be changed between a machining position where it enters the inside of the container in the second state and a retracted position where it retracts to the outside of the container in the first state, and by changing the container from the second state to the first state, gas accumulated inside the container is discharged to the outside of the container.

6. A wire electric discharge machining method for electric discharge machining the workpiece using the wire electric discharge machining device according to any one of claims 1 to 5, comprising: a filling step of filling the interior of the container with the machining fluid before the start of electric discharge machining, creating a space inside the container filled with the machining fluid to a position above the liquid surface of the machining fluid in the machining tank; and a machining step of performing electric discharge machining while moving the workpiece, and moving the workpiece into the interior of the container as the electric discharge machining progresses.

7. A wire electric discharge machining method for electric discharge machining the workpiece using the wire electric discharge machining device according to any one of claims 1 to 5, characterized in that it includes a machining step of lifting the upper surface of the container, filling the inside of the container with the machining fluid, creating a space inside the container filled with the machining fluid up to a position above the liquid surface of the machining fluid in the machining tank, moving the workpiece to perform electric discharge machining, and causing the workpiece to enter the inside of the container as the electric discharge machining progresses.

8. A wire electric discharge machining method for electric discharge machining the workpiece using the wire electric discharge machining device according to claim 1 or 5, comprising: a filling step of, before the start of electric discharge machining, lifting the top surface of the container, filling the inside of the container with the machining fluid, and creating a space inside the container filled with the machining fluid to a position above the liquid level of the machining fluid in the machining tank; a machining step of performing electric discharge machining while moving the workpiece, and causing the workpiece to enter the inside of the container as the electric discharge machining progresses; a retracting step of retracting the workpiece to the outside of the container if a certain amount of gas has accumulated inside the container during electric discharge machining; a discharge step of pushing down the top surface of the container towards the opening to contract the side surfaces, thereby discharging the gas accumulated inside the container to the outside of the container; and a resumption step of lifting the top surface of the container in a direction away from the opening to expand the side surfaces, and then causing the workpiece to enter the inside of the container and resuming electric discharge machining. A wire electric discharge machining method, characterized in that electric discharge machining is performed by repeating the machining step, the retracting step, the discharging step, and the resuming step.

9. A wire electric discharge machining method according to claim 8, further comprising an adjustment step between the machining step and the retraction step for adjusting the voltage applied between the wire electrode and the workpiece when a certain amount of gas accumulates inside the container during electric discharge machining, and wherein electric discharge machining is performed by repeating the machining step, the adjustment step, the retraction step, the discharge step, and the resumption step.

10. A wire electric discharge machining method for electric discharge machining the workpiece using the wire electric discharge machining device according to claim 1 or 5, comprising: a machining step of lifting the top surface of the container, filling the inside of the container with the machining fluid, creating a space inside the container filled with the machining fluid up to a position higher than the liquid level of the machining fluid stored in the machining tank, while moving the workpiece to perform electric discharge machining, and causing the workpiece to enter the inside of the container as the electric discharge machining progresses; a retracting step of retracting the workpiece to the outside of the container when a certain amount of gas has accumulated inside the container during electric discharge machining; a discharge step of pushing down the top surface of the container towards the opening to contract the side surfaces, thereby discharging the gas accumulated inside the container to the outside of the container; and a resumption step of lifting the top surface of the container in a direction away from the opening to expand the side surfaces, and then causing the workpiece to enter the inside of the container and resuming electric discharge machining. A wire electric discharge machining method, characterized in that electric discharge machining is performed by repeating the machining step, the retracting step, the discharging step, and the resuming step.

11. A wire electric discharge machining method according to claim 10, further comprising an adjustment step between the machining step and the retraction step for adjusting the voltage applied between the wire electrode and the workpiece when a certain amount of gas accumulates inside the container during electric discharge machining, wherein the electric discharge machining is performed by repeating the machining step, the adjustment step, the retraction step, the discharge step, and the resumption step.

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